Binder for peroxid active material and process of making it.



No Drawing.

UNITED STATES PATENT OFFICE.

wrnnmmmonmsou, or one MOINES, IOWA.

BItNDER-FOR rnaoxin ACTIVE-MATERIAL AND- raocnss or MAKING IT.

To all whom it may concern:

Be it known that'I, WILLIAM NIORRISON, a

citizen of the United States, residing at Des Moines, in the county of Polk and State of Iowa, have invented certain new and useful Improvements in Binders for -Peroxid Active Material and Processes of Making Them, of which the following is a specification.

This invention relates to the production of a permanent and insoluble binder'for the active material of the positive-pole electrodes of lead storage batteries. This binder fundamentally comprises an oxygen-compoundof a metal or metals incapable ofdirectly replacing hydrogen in a sulfuric acid compound of tantalumv as the binder.

this purpose, a metallic support, for example a grid of ant-imonial lead, is. pasted or filled with the'usual mixture of minium, litharge and sulfuric acid solution, in which mixture lead sulfate forms as a provisional binder.

Complete formation, or peroxidation, of the active material'is then preferably initially effected by placing the pasted grids, alternately with unfilled grids serving as dummy electrodes of the opposite polarity, in a sulfuric acid solution having a spe cific gravity of 1.200 to 1.250and passing an electric current-through the solution, alternately. in opposite directions, until the paste has been sufficiently expanded, care being taken not to force the discharge beyond the normal intended capacity of the electrodes.

The formed and dummy electrodes are then removed from the sulfuric acid solution and placed in a cell containing water, and electric current is passed from the filled electrodes to the dummies until the free acid in the active material has been removed. The electrodes and dummies are then removed,

Specification of Letters Patent.

For

' constitutes the binder.

Patented Apr. 2, 1912.

Application filed Februai'y 23, 1912. Serial No. 679,298.

rinsed in water, and placed in a strong aqueous solution of an alkali-metal tantalate, for example potassium hexatantalate. An, electric current is then passedfrom the filled electrodes through thesolution to the dummies, and is continued for several hours, thereby causing tantalum ions, presumably complex tantalum-oxygen ions, to penetrate the active material to any desired degree and to combine chemically with the leadoxygen compounds thereof, and particularly with the lead sulfate which serves as the provisional binder in the electrode. The electrodes and dummies are then removed, rinsed in water, placed in a sulfuric acid solution having a specific gravity of about 1.300, and an electric current is passed from the electrodes to the dummies until all of the soluble foreign constituents of the active material have been removed or rendered in-' soluble. The electrodes are then discharged to the extent of their normal capacity, and thereafter recharged, preferably to some what less than their full capacity, in another sulfuric acid solution of 1.280 specific gravity, the effect of such incomplete recharging being to leave in the plate a certain proportion of lead sulfate to combine with the tantalum ions on a repetition of the treatment, should such repetition be desired, for the purpose of impregnating th factive material with an additional amount of the binder compound. Atthe conclusion of the treatment the positive-pole electrodes are mounted in connection with the regular negative plates, and receive their full normal charge. The object of performing the preceding operations with dummy electrodes instead of with the regular battery electrodes is to prevent injury to the latter by combination of tantalum therewith or by deposition of impurities therein. Positivepole electrodes prepared as described I are not suited for forming negative electrodes by reversal, since negati e electrodes thus formed undergo discharge by iocal action.

The tantalum-oxygen anion appears to play the same role in the binder compound as does the sulfur-oxygen anion in the ordinary lead electrodes in which lead sulfate The lead-tantalumoxygen compound is however, as compared with the lead sulfate heretofore commonly used as a binder, very permanent and insoluble,-being chemically and electrochemically one, it is sometimes preferable, particularly with thick plates, in order uniformly to distribute the binder throughout the active mass, to incorporate the binder, or a portion thereof, with the active material by another method, which will now be described. This method consists in forming an aqueous solution of a suitable lead salt, as lead nitrate or acetate, adding a soluble tantalate, for example potassium hexatantalate, niobate or tungstate, until all the lead is prec1p1 tated, separating the precipitate and washing 1t with dilute sulfuric acid, then boiling it 1n strong sulfuric acid and Washing it with water. The precipitated tungsten compound, when used as the-binder, should be heated nearly or quite to its melting point, in order to give it a denser body. Heating is optional with the tantalum and niobium precipitates. The desired proportion of this product is very thoroughly mixed with the minium-litharge paste, as by grlnding the materials. together.

The foregoing methods may be used singly or together as desired, but if used together it is preferred to use the electrolytic method as the finishing stage.

It is to be understood that the several foregoing examples are illustrative in character, and that the invention is not limited to the details of manipulation or to the strength or proportions of reagents recited; and it is also to be understood that the positive-pole electrodes may be" prepared by methods other than those herein specifically described without departure from my invention Positive-pole electrodes having a binder containing both tantalum and niobium may be prepared by either or both of the methods above described, a mixture of a soluble tantalate and niobate being used either as an electrolyte in the first method, or as a precipitantfor the lead salt in accordance with the second method. As these two metals commonly occur together in ores, and as it is difficult and expensive to separate them, it is often commercially preferable to thus use both in the binder.

When the tantalumcompound, or mixture of tantalum and niobium compounds, is pro- I 'duced by precipitation, according to the sec-v ond method described, and subsequently bium in its acidic radical.

addedto the active material, it not only serves to bind this material but-also gives it porosity.

I claim:

1. Active material for positive-pole lead electrodes, comprising a compound cont-aining tantalum.

2. A permanent binder for the active material of positive-pole lead electrodes, consisting of a compound having tantalum in its acidic radical.

3. A permanent binder for the activematerial of positive-pole lead electrodes, consisting of a lead compound having tantalum in its acidic radical.

4. A permanent binder for the active material of positive-pole lead electrodes, consisting of a compound containing oxygen, lead and tantalum.

5. A permanent binder for the active material of positive-pole lead electrodes, consisting of a compound containing oxygen, sulfur, lead and tantalum.

6. A permanent binder for the active material of positive-pole lead electrodes, consisting of a lead compound having tantalum and niobium in its acidic radical.

7. A permanent binder for the active material of positive-pole lead electrodes, consisting of a compound containing oxygen, sulfur, lead, tantalum and niobium.

8. In a process of binding the active material of positive-pole lead electrodes, the step which consists in impregnating it with a compound containing tantalum in its acidic radical.

9. In a process of binding the active material of positive-pole lead electrodes, the step which consists in impregnating it with a compound containing tantalum and nio- 1 0. In a process of binding the active material of pos1t1ve -pole lead electrodes, the steps which consist in reacting on a solution of a lead salt with a compound of a metal incapable of directly replacing hydrogen in a sulfuric acid solution; insoluble by anodic oxidation in a sulfuric acid solution; incapable of cathodic reduction to metal, or of electrolytic separation as metal, in a sulfuric acid solution; and capable of forming complex anionsv with electro-negative elements, and incorporating the reaction-product with the active material.

11. In a process of binding the active material of positive-pole lead electrodes, the steps which consist in reacting on a solution of a lead salt with a compound of a metal incapable of directly replacing hydrogen in a sulfuric acid solution, insoluble by anodic oxidation in a sulfuric acid solution; incapable of cathodic reduction to metal, or of electrolytic separation as metal, in a sulfuric acid solution; and capable of forming complex anions with electro-negative elements, heating the reaction-product and incorporating it with the active material.

12. The process of producing positive-pole lead electrodes having active material containing a permanent binder, which comprises the steps of reacting on a solution of a lead salt with a compound of a metal incapable of directly replacing hydrogen in a sulfuric acid solution, insoluble by anodic oxidation in a sulfuric acid solution; incapable of cathodic reduction to metal, or of electrolytic separation as metal, in a sulfuric acid solution; and capable of forming complex anions with electro-negative elements; mixing the product with the active material; applying the mixture to a support to constitute an electrode; passing an electric current from the electrode through a solution of a compound having in its acid radical a metal incapable of directly replacing hydrogen in a sulfuric acid solution; in

soluble by anodic oxidation in a sulfuric acid solution; incapable of cathodic reduction to metal, or of electrolytic separation as metal, in a sulfuric acid solution; and

capable of forming complex anions with electro-negative elements, thereby impregnating the active-material with a compound of said metal, and reacting on said compound with. sulfuric acid. 313'. The process of producing positivepo le lea'd electrodes having active material ,qpo'ntaining apermanent binder, which compr ises;th esteps of reacting on a solution of a lead salt with a tantalate, thereby impregnating the active material with a compound of tantalum, and electrochemically reacting on said compound with sulfuric acid. c

14. In a process of binding the active material of positive-pole lead electrodes, the steps which consist in reacting on a solution of a lead salt with a compound of tan-- talum, and incorporating the reaction-product with the active material.

15. In a process of binding the active material of positive-pole lead electrodes, the steps which consist in reacting on a solution of a lead salt with compounds of tan' talum and niobium, and incorporating the reaction-product with the active material.

16. In a process of binding the active material of positive-polelead electrodes, the steps which consist in reacting on a solution of a lead salt with a compound of tantalum, incorporating the reaction-product with the active material, applying the mixture to a support to constitute an electrode,

passing an. eectric current from the electrode through a solution of a tantalate,-

thereby impregnating the active material with a compound of tantalum, and reacting on said compound with sulfuric acid.

17'. In a process of binding the active mai 18. In a process of binding the active material of positive-pole lead electrodes, the steps which consist in reacting on a solution of-a lead salt with a compound of tantalum, incorporating the reactionprodu'ct with the active material, applying the mixture to a support to constitute an electrode, passing an electric current from the electrode through a solution of a tantalate and a niobate, thereby impregnatin the active material with a compound of tantalum, and

electrochemically reacting on said compound with sulfuric acid;

19. In a process of binding the activematerial of positive-pole lead electrodes, the steps which consist in reacting on a solution of a lead salt with compounds of-tantalum and niobium, incorporating the reaction-product with the active material, applying the mixture to a support to ,constitute an electrode, passing an electric current from the electrode through a solution of a tantalateand a niobate, thereby impregnating the active material with a compound of tantalum, and electrochemically reacting on said compound withisulfuric acid.

In testimony whereof I affix my signature v in presence of two witnesses.

. l/VILLIAM MORRISON.

Witnesses:

EUGENE A. BYRNES, N. P. LEONARD. 

